3.2- Transport In Animals
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- Created by: McTighe
- Created on: 21-04-18 09:02
Why do small animals not need a seperate transport system?
As they have a large surface area-volume ratio, so their cells are close to the environement, so get nutrients by diffusion
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What are the three main factors that influence the need of a transport system?
-Size -Surface area to volume ratio -Level of metabolic activity
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How does size affect the need for a transport system?
-Cells in large organisms are too far from surface, so diffusion pathway increases, so rate of diffusion decreases (Not efficient). Outer cells will use up all supplies, so less reach deep in body
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How does surface area to volume ratio affect the need for a transport system?
Small animals have large surface area to volume ratio, so each gram of tissue has suffiecent area of body surface where exchange can occur. Large animals do not have this
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How does level of metobllic activity affect the need for a transport system?
Animals release energy from food so they can move around. Releasing energy requires oxygen (aerobic respiration). IF animal is active, cells need a good supply of oxygen. Animals that keep themselves warm need even more energy
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Name 5 factors an effective transport system will have
-Medium to carry nutrients -A pump to create pressure to pump medium -Exchange surfaces which enable substances to enter/leave blood (capillaries). -Vessles to carry blood by mass flow -Two circuits
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What is a single circulatory system?
Blood flows through the heart once each circuit
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Describe the movement of blood through a fish
Heart --> Gills --> Tissues --> Heart
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What is a double circulatory system?
Blood flows through the heart twice in each circuit
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Describe the movement of blood through a mammal
Heart --> Lungs --> Heart --> Tissues --> Heart
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What is the circuit called which picks up oxygen from the lungs?
Pulmonary Circuit
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What is the circuit called which delieves oxygen to the tissues?
Systemic Circuit
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Name three advantages of a double circuit
1. High presure to systemic circuit means blood flows a lot more quickly 2.High pressure allows mammals to be more active, and maintain body temperature 3.Blood pressure is not limited by nature of capillaries
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What is the space called inside a vessel where blood flows?
The Lumen
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What is the tissue called which surrounds the lumen?
Squamous Epithelium
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What is an open circulatory system?
Where blood is not always held in vessels. Blood circulates through body cavity, so tissues are bathed directly in blood
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Name Two disadvantages of an open circuit
1.Blood pressure is low, so blood flow is slow 2.Circulation of blood may be affected by body movements (OR LACK OF)
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What is a closed circulatory system?
Where blood remains completely in blood vessels
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What is the name of the fluid which bathes tissues and cells in a closed circulatory system?
Tissue Fluid
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Name 3 advantages of a closed circulatory system
1. High pressure so blood flows more quickly 2.Rapid delievery of oxygen and removal of CO2 3.Transport independent of body movement
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What is the purpose of the artery?
Carry blood away from the heart
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Why do arteries have a thick wall?
To withstand pressure of blood
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Do arteries have a small or large lumen?
Small
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Why do arteries have a small lumen?
To maintain high pressure (Low blood volume)
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Name the three parts of the artery wall
-Tunica Intima -Tunica Media -Tunica Externa
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Describe the Tunica Intima in the artery wall?
Contains elastic tissue and smooth muscle to allow walls to stretch and recoil to maintain blood pressure. Also contains some collagen fibres
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Describe the Tunica Media in the artery wall?
Contains smooth muscle and elastic fibres and some collagen fibres
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Describe the Tunica Externa in the artery wall?
Contans tough collagen fibres to provide strength to withstand high pressure. Also contains elastic fibres to recoil.
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What is another name for the Tunica Externa?
Tunica Adventitia
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Is the blood oxygenated or deoxygenated?
Oxygenated, apart from Pulmonary Artery
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Do arteries have valves?
NO
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What is the function of the arterioles?
Distribute blood from an artery to capillary
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What do the walls of the arterioles contain?
Layer of smooth muscle
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What does the contraction of this muscle help do?
Constrict arteriole, increasing resistance to flow and reduce the rate of flow. This is used to divert blood to more oxygen-demanding regions
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What is the function of the capillary?
Allows exchange of material between blood and tissue fluid
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What tissue makes up a capillary?
Squamous Endothelium
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Why is a capillary only one cell thick?
Reduces diffusion distance
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How do leaky walls hep the capillary to carry out its function?
Blood plasma and dissolved substances leave blood vessel so substances can exchange easily
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What is the function of the venules?
Distribute blood from capillary to veins
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What do the walls of venules contain?
THin layer of muscle, elastic tissue and collagen
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What is the function of veins?
Carry blood towards heart
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Why are the walls of a vein thin?
Blood is at low pressure
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Why do veins have a large lumen?
To allow ease of flow
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What does the Tunica externa contain?
Collagen fibres
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What does the Tunica Media contain?
Smooth muscle and elastic fibres
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What does the Tunica Intima contain?
Squamous Endothelium
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Do veins contain valves?
YES- Semi lunar valves
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How do the semi lunar valves help veins function?
They prevent backflow of flood.
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Name some dissolved substances found in blood plasma
Amino acids, carbon dioxide, oxygen, hormones, glucose, mineral ions
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Describe the process of tissue fluid
High hydrostatic pressure at arteriole pushed blood out of capillaries. Plasma proteins remain in blood as too large, lowering water potential. -Oncotic pressure pushes water into capillary (But does not outweigh net movement).
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CONTINUED
-Tissue fluid surrounds body cells, so exchange of gases and nutrients occur (Facilitated diffusion and active transport). Blood pressure at venous end is much lower, allowing tissue fluid to return to capillary with waste products
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How much of the tissue fluid moves back into the capillaries?
90%
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Where does the other 10% go?
Lymphatic system
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What does the fluid become?
Lymph
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What is the purpose of the lymphatic system?
This drains excess tissue fluid out of tissues and returns to blood system in chest. It also allows proteins to move in to the body (Too big to move through capillary)
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What is the vein called where this lympathic system returns to?
Subclavian vein
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Does the lympathic system contain less or more lymphocytes?
More
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Where are these lymphocytes formed?
Lymph nodes
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Which side of the heart pumps oxygenated blood?
Left side
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Where in the body in the heart found?
Located off centre towards the left of the chest cavity
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What divides the heart into left and right?
septum
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What is the purpose of the septum?
To ensure oxygenated and deoxygenated blood do not mix
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What is each side divided into?
Atriums and Ventricles
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What is the name of the artery which supplies the heart oxygen and nutrients?
Coronary Artery
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WHat happens if the Coronary artery becomes blocked?
Restricted blood flow to heart muscles reducing delivery of oxygen
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Name two medical problems this can cause?
Angina or Heart attack
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What do Atriums recieve deoxygenated blood from?
Vena Cava
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What do Atriums recieve oxygenated blood from?
Pulmonary Vein
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What do ventricles remove oxygenated blood with?
Aorta
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What do ventricles removed deoxygenated blood with?
Pulmonary Artery
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What are the atriums and ventricles seperated by?
Atrioventricular valves
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What are the valves attached by?
Tendinous Cords
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What is the purpose of the tendinous cords?
Prevent valves from turning inside out when ventricular walls contract
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What separated the ventricles from the aorta and pulmonary artery?
Semi-lunar valves
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Describe the blood pressure in atria
Muscle walls are thin as they do not need to create a lot of pressure. Their function is to receive blood from veins and push into ventricles (Not far)
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Describe the blood pressure in right ventricle
Walls are thicker than atria as it pumps deoxgeneted blood to lungs. Lungs in chest cavity so not far. Alveolar are delicate, so high blood pressure can damage them
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Describe the blood pressure Left ventricle
Walls are thicker than right as blood needs to be pumped through aorta and needs sufficent pressure to overcome resistance of systemic circulation. Blood has to go through whole body, so higher pressure as it needs to come back again
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Describe cardiac muscle
-Contains fibres that branch, producing cross-bridges. -Spread around heart and ensure contraction -Lots of mitochondria between muscle fibrils supply energy for contraction -Muscle cells separated by intercalated discs which synchronise contraction
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What are muscle fibrils called?
Myofibrils
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What is the cardiac cycle?
The sequence of events in one full heart beat
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What is the period called when the heart is contracting?
Systole
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What is the period called when the heart is relaxing?
Diastole
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Describe Diastole
Elastic recoil causes chambers to increase in volume (lowers pressure), so blood flows in from veins. Semi-lunar values are closed but atrioventricular valves are open
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Describe Atrial systole
Atria contracting at same time to push blood into ventricle. Atrioventricular valves are open, semi-lunar valves are closed
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Describe Ventricular systole
Ventricles contracting at same time (contractions start at apex upwards) so blood pushed up to arteries. Atrioventricular valves closed, semi-lunar valves open
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What creates the heart sounds 'LUB DUB'
The closing of atrioventricular valves and semi-lunar valves
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Why does the pressure in capillaries reduce?
Due to increase total cross-sectional area
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What is the term for the heart being able to coordinate its own contractions?
Myogenic
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Which muscle contracts at a higher frequency? (Ventricular or Atrial)
Atrial
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What is condition called if the atria and ventricles were uncoordinated?
Fibrillation
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Where does the iniation of a heart beat start?
Top of right atrium, Sino-atrial node generated waves of excitation at regular intervals
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What happens to the wave of excitation?
Waves spread throughout atrial muscle, causing atrial systole to occur. It will stop when it reaches base of atia
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Why do the waves stop at the bottom of the atria?
They reach a non-conducting disc of tissue, preventing the waves from contracting ventricles too early.
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What creates waves of excitation in the ventricles?
At top of interventricular septum, the atrioventicular node produces waves. They can only move down specialsied tissue
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What is this specialised tissue called?
Bundles of His
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How do the ventricles contract?
The waves spread from apex and upwards, through the Purkinje fibres, creating ventricular systole
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What is an electrocardiogram?
A device that measures electrical activity of the heart. Sensors are placed around body, connected to a monitor and senses the electrical signals that spread from the heart to skin
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What does the P represent in an electrocardiogram?
Excitation of Atria (Atrial systole)
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What does the QRS represent in an electrocardiogram?
Excitation of ventricles (Ventricular systole)
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What does the T represent in an electrocardiogram?
Diastole
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What is the term used for a slow heart beat?
Bradycardia
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What is the term used for a fast heart beat?
Tachycardia
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What is the term used for atria beating faster than ventricles so no P waves are seen?
Atrial Fibrillation
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What is the term used for a third heart beat as an early ventricular beat?
Ectopic
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What is called when oxygen binds to Haemoglobin?
Oxyhaemoglobin
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How many subunits does haemoglobin have?
four
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What does each subunit of haemoglobin contain?
Polypeptide chain and a haem group
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What does the haem group do?
Attracts and holds oxygen. (each haem group holds one oxygen molecule)
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The haem group has ....... ........ for oxygen
High affinity
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When does the association of oxygen and haemoglobin occur?
When the partial pressure of oxygen is high (pO2)
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What is it called when oxyhaemoglobin releases oxygen?
Dissocation
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What is partial pressure of oxygen measured in?
kPa
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What shape on a graph does haemoglobin association with oxygen form?
S shape
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Why does haemoglobin not react readily with oxygen at low oxygen tension?
The haem groups are in the centre of the haemoglobin molecules, so it is difficult for oxygen to reach haem group
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Why does haemoglobin act more readily at higher oxygen tensions?
Eventually an oxygen molecule enters haemoglobin molecule, causing a change in haemoglobin molecule and allows more oxygen to enter the molecule and associated with haem groups more easily
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What is this change in haemoglobin shape called?
Conformational change
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Why does the graph curve off as it reaches 100% saturation?
Mammalian haemoglobin is adapted to transporting oxygen to tissues. Oxygen tensions found in lungs is sufficient to produce 100% saturation. Oxygen tension in respiring body tissues is sufficiently low to cause oxygen to dissociate readily from oxyha
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Why does fetal haemoglobin have a higher affinity for oxygen?
Fetal haemoglobin must be able to associate with oxygen in an environment where oxygen tension is low enough to make adult haemoglobin release oxygen.
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Name the three ways carbon dioxide is transported (and percentages)
5% dissolved directly in blood, 10% combined with haemoglobin to form carbaminohaemoglobin, 85% transported in hydrogencarbonate ions (HCO3-)
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Describe how hydrogencarbonate ions are made
CO2 in blood plasma diffuses into red blood cell and combines with H2O to form Carbonic acid. This carbonic acid dissociates to release hydrogen ions and hydrocarbonate ions
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What enzyme catalyses the dissociation of carbonic acid?
Carbonic anhydrase
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What is the Chloride shift?
Hydrogencarbonate ions dissude out of red blood cell into plasma, but chloride ions move in to maintiain charge
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How is haemoglobinic acid formed?
Hydrogen ions are taken out of solution by associating with Haemoglobin. Haemoglobin acts as a buffer to maintain pH
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Why does oxyhaemoglobin dissociate>
Low of pO2 and under influence of hydrogen ions (Hydrogen ions join with haemoglobin to form haemoglobinic aicd)
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Other cards in this set
Card 2
Front
What are the three main factors that influence the need of a transport system?
Back
-Size -Surface area to volume ratio -Level of metabolic activity
Card 3
Front
How does size affect the need for a transport system?
Back
Card 4
Front
How does surface area to volume ratio affect the need for a transport system?
Back
Card 5
Front
How does level of metobllic activity affect the need for a transport system?
Back
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